Labour Party finance spokeswoman Joan Burton has surprised colleagues by announcing she will not be contesting the leadership of the party, but will be seeking the deputy leadership instead.
Ms Burton was regarded as the strongest possible challenger to the only declared candidate for the leadership to date, Eamon Gilmore, the firm favourite for the job.
The current acting leader of the party, Liz McManus, reiterated last night she would not announce her leadership intentions until after the Labour Party national executive meeting on Saturday.
The meeting is expected to set next Thursday as the deadline for close of nominations for leader and deputy leader.
The other TD still considering entering the race, Dublin North East's Tommy Broughan, said last night he would announce his decision today. He said last night he was still consulting colleagues.
Dublin Central TD Joe Costello, who is on holiday in Cuba, told The Irish Timeshe had not yet made a final decision but he did not expect to declare for either the leadership or deputy leadership. He returns to Ireland next Thursday.
He said he, like other members of the party, was taken by surprise at Pat Rabbitte's announcement, and he hoped there was a leadership contest.
To date, Ms Burton and Limerick East TD Jan O'Sullivan have declared for the deputy leadership. Cork South Central TD Ciarán Lynch said he was also considering running for this position.
Wexford TD Brendan Howlin and Róisín Shortall of Dublin North West this week ruled themselves out of the contest.
Last night Ms Burton - who will be proposed for the deputy leadership by Waterford TD Brian O'Shea and seconded by newly-elected Dublin Mid-West TD Joanna Tuffy - promised to mount a robust campaign.
She said she decided not to run for the leadership after discussions with party members in the past week. "I recognise that I do not have sufficient support to continue with any bid for the leadership."
She added that there was a genuine groundswell of support to elect her as deputy leader, and said she was the most inclusive candidate who could represent the wishes and ambitions of all the members.
"I promise the members that I will promote a thorough look back to learn the lessons of the strengths and weaknesses of our May 2007 result. Both our victories and our losses can yield fruitful lessons for the future," she added.
Meanwhile, Ms Tuffy joined the number of TDs who have publicly announced their support for Mr Gilmore in the leadership race. She said she believed he would continue the process of growing the party.
Former leader Ruairí Quinn, Michael D Higgins and party chief whip Emmet Stagg have also declared their support for Mr Gilmore.